modelling Schottky Diode

[bhatt_190487]

I am modelling the nonlinear diode in ADS to get the characteristics of Agilent's 5082 -2800 Schottky Diode. I am getting I-V curve but when I apply RF power signal to the diode , the RF resistance is not changing . The dynamic resistance remains constant with the increasing input power. Please help me out to solve the problem. My model parameters are. Rs =32 ohm , N=0.639 ohm, rest all default.Thank you in advance.

 

[Abhishekabs]

If your Model is correct then it should work. Try Changing parameters or attributes during simulation.
Also try putting some termination at diode end like capacitor and check!?

 

[BradtheRad]

Dynamic resistance is very high at low volt levels. It falls rapidly as you raise voltage each tenth of a volt.

The equation might resemble something like A = 50000 * V^8.

The diode has a certain amount of innate ohmic resistance. However it does not come into play much at low voltage/current levels.

As you apply greater voltage/current, the diode's dynamic resistance falls to near zero. Then ohmic resistance becomes dominant. The diode displays linear response.

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By the way, my equation above is not derived mathematically from real diode parameters.

My equation is just a best attempt to match the I/V curve we might obtain by taking measurements.

My equation shows the I/V relationship is exponential. The diode's resistance varies enormously over the range of a few tenths of a volt.

 

[bhatt_190487]

Thank you for your reply . I have attached capacitor as dc block and resistor at the termination end.But still no change in dynamic resistance is received . Please help me out.

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I have tried changing all parameters during simulation but there is no change in the dynamic resistance with change in RF power

 

[bhatt_190487]

schottky diode modelling

I am modelling Schottky diode using PN junction diode in ADS.I got Spice model parameters from Agilent's Schottky diode datasheet . By changing N,IS and R I could get my required I-V curve. But ,there is no change in the dynamic resistance of the device ,when RF power signal is applied to it.

Please help me to solve my problem.

1.Which parameter change affects the dynamic resistance?

2.What Should I change in the model to have effect on dynamic resistance with change in RF signal?

3.How can I know whether the Device is modelled as Schottky diode or not ?

4.What are the modelling steps after I-V curve is obtain, to get dynamic resistance changed?

4.Can the spice model parameters directly be used in ADS or some process is required?

 

[BradtheRad]

Perhaps an answer will emerge if you compare ordinary diodes to the diode you are talking about, and ordinary diode usage to the usage you are talking about.

* What is the difference between an ordinary diode and a Schottky diode?

* What is the difference if you apply rf frequencies versus applying ordinary frequencies? Are you interested in its speed of recovery?

Are you familiar with the Shockley diode equation? It includes factors that govern diode response. (Not saying I know how to apply the equation.)
See Wikipedia's article below.

https://en.wikipedia.org/wiki/Diode_modelling

 

[dick_freebird]

Cj0, m and phi will affect the C-V swing (and these will be way
different than a PN junction diode).

I would bet that Agilent provides ADS and/or SPICE models
good-to-go for this part. Have you dug into their support
pages looking for model libraries?

 

[RealAEL]

This device is now from Avago and not Agilent. The data provided at

**broken link removed**

Includes a Spice model with RS=25 Ohms and N=1.08.